Electron discharge system



May 15-, 1934. R. L DOWNEY ELECTRON DISCHARGE SYSTEM Filed April 18, 1933 Fig.1.

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'IIII'I'IJ'IIIIIIIIIII'IIA IIYII'J II IIIII Irwventorw Reginald L. Downs g by WM I His Attorney.

Patented May 15, 1934 UNITED STATES PATENT OFFICE.

ELECTRON DISCHARGE SYSTEM New York Application April18,

4 Claims.

My invention relates to electrondischarge systems and, while generally applicable thereto, has particular utility in connection with constant frequency electron discharge oscillation-generators.

One of the objects of my invention isto provide means for use particularly in connection with constant frequency electron discharge systems whereby the cathode of the discharge device employed may be operated above ground'operating potential without-encountering difliculties due to the size of certain elementsof the energizing circuit of the cathode, or due to variations in the operating characteristics of the circuits of the discharge device caused by changes in the constants of the cathode energizing transformer which may, in turn, be caused, for example, by the heating of the cathode transformer by the cathode energizing currents.

A further object of my invention is to provide means whereby these results are secured and whereby the entire system including the cathode energizing transformer and filtering means may be enclosed in a temperature controlled chamber of relatively small dimensions.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appendedclaims. My invention itself, however, both as toitsorganization and method of operation together with further objects and advantages thereof may best be understood by reference to the following description taken in connection with the accompanying drawing in which Figs. 1 and 2 represent different embodiments of my invention.

Referring to Fig. 1, I have shown therein an electron discharge device 1 provided with circuit connections whereby it is arranged for operation as an oscillation generator. This dischargedevice includes an anode 2, a screen grid 3, anda control grid 4. An oscillatory circuit 5, tuned'to any desired frequency, is connected between-the two grids 3and 4 through suitable condensers 6 and '7. The side of the oscillatory circuit which is connected to the screen grid 3 is grounded at 8 whereas an intermediate point on the oscillatory circuit is connected through a conductor 9 and condensers 10 to the cathode. The cathode of the discharge device-is energized from a source of electromotive force 11 through acathode transformer 12, and the anode of the discharge device is energized from a source of electromotive force 13 which is connected between the anode and an intermediate point on the secondary winding of the transformer 12. The positive terminal of this source is connected to the anode through a suit- 1933, Serial No. 666,731

ableresistance 14 shunted by coil '15, and the negative side of the source is connected to the intermediatepoint on the transformer through a high frequency choke coil'16. Resistance 14 comprises the coupling resistance between the oscillator shown and the load, not shown, whichmay comprise an electron discharge amplifier. The inductance 15 is a low resistance direct currentpath about this resistance having high impedance to the oscillations producedr Theusual grid leak 1'7 P is provided between the control grid l i and the cathode connection. The load device, not shown, may be connected to the anode of the discharge device through acondenser 18-, the opposite side of the load'device being connected to ground.

As, thus arranged oscillations are excited in the oscillatorycircuit 5 due to actionof thecathode, control grid 4, and screening grid 3 of thedischarge device. The anode 2' of the discharge device is electronically coupled-to the electrodes3 and 4, and isthereby adapted to receive oscillations-havingthe frequency at which the circuit-5 is resonant, or a desired harmonic thereof, oscillations of thesefrequencies being supplied to the load device.

It is desirable in the operation of the system, however, thatthe coupling between the anode 2 and the control grid 4 should be solely electronic coupling and that capacitive-coupling should be eliminated. For this reasonthe screen grid 3 is maintained 'at, ground alternating potential by means of the condenser 7. This-screen grid thus serves to eliminate capacitive coupling between the anode 2 and grid.4.

Owing to the fact that this screen grid 3 is grounded at the point 8 and the intermediate point on the oscillatory circuit isrconnected to the cathode the cathode operates at a potential above ground. Accordingly unless further means he provided variations in the constants of the cathode energizing transformer, such as due to heating of the transformer by the energizing currents, will affect the characteristics of the operating. circuits of the discharge device and may influence the frequency thereof. To avoid these effects I employ. the condensers 10 connected across the secondary windingof the transformer, condenser 19 connected across the primary of the transformer, andcondensers 20and 21 connected between the primary and secondary of the transformer at the opposite ends thereof, whereby the change in. characteristics, ofthistransformer is prevented from in any wise affecting the operation of the discharge device. Of course, the transformer may be isolated from the high frequency circuits of the discharge device by means of high impedance choke coils connected in the secondary circuit of the transformer. In systems, however, where the cathode of the discharge device requires heating current of considerable magnitude these must be of large current carrying capacity and hence are of objectionable size and expense. In accordance with my invention the use of coils of such objectionable size is avoided by placing the transformer in the high frequency portion of the circuit and by-passing it with the condensers 10, 19, 20, and 21 as above described. The flow of currents of the frequency produced by the oscillator in the cathode circuit leading to the source 11 may then be avoided by having relatively small choke coils 22 having high impedance to the oscillations produced and low impedance to cathode energizing current and having low current carrying capacity placed in the primary circuit of the transformer and by by-pass condensers 26 leading to ground at 27. This is made possible by the fact that the transformer is of step-down ratio having its low current winding connected to the source. As thus arranged the entire system may be enclosed in a temperature control chamber 23 provided with a heater 24 and temperature responsive regulator 25 for the heater. The choke coils 22 and the cathode transformer 12 may both be enclosed within the chamber 23 and at the same time this chamber may be of relatively small dimensions.

Fig. 2 shows a different embodiment of my invention in which the discharge device is one of the three-element type the oscillatory circuit being connected between the anode and the grid thereof, and the cathode being connected at an intermediate point on the oscillatory circuit whereby it likewise operates at a point above ground potential. The anode of the discharge device is grounded at the point 30. The load circuit 31 may then be connected between the cathode and ground. The cathode energizing circuit is the same as that previously described, the choke coils 22 being included in the low current high voltage circuit of the cathode energizing transformer whereby they may be of small dimensions such that they may be enclosed in the temperature control chamber 23 and at the same time be effective to prevent the flow of currents of the operating frequency to the source of cathode energizing currents 11 and to ground at 27. The cathode transformer 12 is shunted by condensers as previously described to render operation of the system independent of the varying constants of the transformer.

While I have shown particular embodiments of my invention it will of course be understood that I do not wish to. belimited thereto since different modifications in the circuit arrangementand instrumentalities employed and varying applications of the principles disclosed may be made. 1', of course, contemplate by the appended claimsto cover any such modifications and applications of my invention as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent in the United States is:

1. In combination, an electron discharge device, circuit connections for said discharge device arranged for operation at a certain frequency, a transformer included in said circuit connections having a secondary winding connected across the cathode of said discharge device to supply energizing current thereto, and having a primary winding connected to a source of cathode energizing electromotive force, means included in said circuit connections whereby said transformer is maintained at an alternating potential with respect to ground, said potential having said certain frequency, and means to prevent variations in the constants of said transformer from affecting the electrical constants of said circuits.

2. The combination, in an electron discharge oscillator, of an electron discharge device having a cathode and a plurality of additional electrodes, an oscillatory circuit connected between two of said additional electrodes, one side of said oscillatory circuit being connected to ground and a point on said oscillatory circuit electrically removed from said one side being connected to said cathode, whereby said cathode is maintained at an alternating electromotive force with respect to ground, a source of energizing current for said cathode, means to ground said source of energizing current with respect to the frequency of oscillations produced by said oscillator, a transformer having its output connected across said cathode and its input connected across said source, means to maintain said transformer at the same alternating potential with respect to ground as said cathode, and means to prevent variations in the electrical constants of said transformer from affecting the frequency of oscillations produced by said oscillator.

3. In combination, an electron discharge device, circuit connections therefor arranged for operation at a certain frequency, a source of heating current for said cathode, a transformer having a high current winding connected to said cathode and a low current winding connected to said source, said transformer and cathode being included in a portion of said circuit such that they are above ground potential of said certain frequency, means connected between said transformer and source having low current carrying capacity and low impedance to said heating currents and high impedance to currents of said certain frequency and means to prevent changing characteristics of said transformer from aifecting the operation of said circuit connections.

4. In a temperature controlled oscillation generator, an electron discharge device having a cathode and a plurality of other electrodes, connections between said cathode and said other electrodes to cause said device to produce oscillations and to maintain said cathode at an alternating potential having the frequency of said oscillations with respect to ground, a constant temperature chamber, said discharge device and connections being enclosed in said constant temperature chamber, a source of cathode heating potential of high voltage, a transformer enclosed in said chamber having a high voltage winding connected to said source and a low voltage winding connected to said cathode, a choke coil having low current carrying capacity and high impedance to said oscillations connected between said source and said high voltage winding and enclosed in said chamber, and means whereby changes in the constants of said transformer are prevented from affecting the frequency of oscillations produced.

REGINALD L. DOWNEY. 

